Most known helmets are usually provided with a transparent visor to prevent the entry of dust or dirty particles and cold wind, and which covers the window opening in the central region of the front side of the helmet. The two end portions of the visor are pivotally disposed on either sides of the helmet near the wearer's ears. As is commonly known, the wearer often needs to lift up the visor to get some fresh air, especially during hot summer days or traffic jams or when waiting for the change of traffic lights at road junctures. Once the traffic gets moving, the wearer pulls down the visor and starts on the road again. This repetitious lifting up or pulling down of the visor is very troublesome.
Moreover, designs of conventional helmets require the use of the hand to move up or down the visor. Even though there is also a kind of helmet provided with a push button switch on the helmet body to manipulate the visor, it still requires manual operation; improvement thereon is therefore necessary.